Influence of Ionic Liquids on the Morphology of Corn Flour/Polyester Mixtures

Polymer mixtures based on native corn flour and synthetic biodegradable polyester are prepared in one processing step. Melt mixing is performed in a laboratory micro-compounder. Starch contained in native corn flour is plasticized either by commonly used glycerol/water mixture or by two types of ionic liquids, 1-allyl-3-methylimidazolium chloride, and 1-butyl-3-methylimidazolium chloride. Efficiency of plasticizers on the compatibility of native corn flour with polyester and starch plasticizing ability is evaluated and compared. The structure of mixtures is examined using scanning electron microscopy and wide-angle X-ray scattering. It is found that the plasticizer applied has a crucial effect on the resulting morphology. Both ionic liquids show a better plasticizing effect on starch compared to the traditional glycerol/water plasticizer. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimMinistry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504

What we learn from resolving dispersion and polarization interactions of ionic liquids

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Structural effects on dynamic and energetic properties of mixtures of ionic liquids and water

International audienceThe aim of this study is to improve our understanding of the microscopic and macroscopic properties of mixtures of ionic liquids with water, in the context of working pairs for absorption heat cycles. We report a molecular dynamics study of dynamic properties (viscosity and diffusion coefficients), water solvation (free energy and local solvation environments) and hydrogen bonding in mixtures of six ionic liquids with water, at two concentrations xH2O = 0.104 and xH2O = 0.900. Three anions, methanesulfonate, dicyanamide and acetate; and two cations, N-ethylpyridinium and cholinium, were chosen due to their potential for water absorption and halogen-free structures. Simulation results capture the trends of experimental data, and were interpreted in terms of the molecular structures and interactions. The strength of hydrogen bonding is a major criterion determining the affinity of an ionic liquid towards water. In particular, the cholinium cations compete with water establishing hydrogen bonds with the acetate anions and this is not favourable in terms of water affinity. Dicyanamide anions lead to the systems with lower viscosity

Modeling ionic liquids using a systematic all-atom force field

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Ab initio molecular dynamics simulations of SO 2 solvation in choline chloride/glycerol deep eutectic solvent

International audienceDeep eutectic solvents (DESs) are mixtures of ionic compounds and molecular hydrogen bond donors. Due to the many components and their different interacting subgroups, they give rise to a plethora of many different interactions which can be studied by ab initio molecular dynamics simulations, because within this method all the forces are calculated on the fly and no parametrization prior to the calculation is necessary. Since DESs can be applied in gas capture, for example for SO2 absorption, we performed ab initio molecular dynamics studies of both the pure choline chloride/glycerol DES and the same mixed with SO2. We identified the hydrogen bonding and other specific interactions between all components. With addition of SO2, we observed a decrease in the anion-OH group interplay, because the chloride anions form complexes with the SO2 molecules. Furthermore, the SO2 molecules are incorporated into the hydrophobic network and the interaction between the hydrogen bonds of all OH groups remain constant. This decrease of anion-OH interaction might be responsible for the more fluid state of the SO2-DESs mixture than the pure DES

Cosolvent effect on physical properties of 1,3-dimethyl imidazolium dimethyl phosphate and some theoretical insights on cellulose dissolution

International audienceWith the aim of studying the behaviour of binary mixtures, ionic liquid + molecular solvent, we have combined experimental measurements of density and viscosity at different temperatures and ionic liquid concentrations with atomistic simulations. 1,3-Dimethyl imidazolium dimethyl phosphate was chosen due to its ability to dissolve cellulose from different sources. Three solvents, dimethyl sulfoxide, ethanol and trifluoroethanol were chosen to cover a wide range of solvatochromic parameters. Experimental data were successfully fitted to correlating equations. Volumetric and dynamic properties were calculated by means of atomistic simulations. The effect of coulombic interactions on physical properties was addressed by scaling the partial charges of ionic species. Besides, the influence of hydrogen bond over the measured properties was analysed. Finally, the role of each solvent during the cellulose dissolution in ionic liquids was discussed

Isobutane as a probe of the structure of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids.

International audienceAn experimental study of the solubility and of the thermodynamic properties of solvation, between temperatures (303 and 343) K and at pressures close to atmospheric, of 2-methylpropane (isobutane) in several ionic liquids based on the bis(trifluoromethylsulfonyl)imide anion and on 1-alkyl-3-methylimidazolium cations, [CnC1Im][NTf2], with alkyl side-chains varying from two to ten carbon atoms is presented. The isobutane solubility increases with increasing size of the alkyl side-chain of the cation in the ionic liquid and decreases with increasing temperature (as typical of an exothermal dissolution process). The mole fraction solubility of isobutane varies from 0.904 · 10−2 in [C2C1Im][NTf2] at T = 343 K to 1.002 · 10−1 in [C10C1Im][NTf2] at T = 303 K. The values measured in this work are compared to the behaviour of n-butane in the same ionic liquids published in a previous study (Costa Gomes et al., 2012). Isobutane was found to be significantly less soluble than n-butane in all the ionic liquids. The differences found are interpreted in relation to the molecular structures obtained by molecular dynamics simulations for the solutions of n-butane and isobutane in the studied [CnC1Im][NTf2] ionic liquids

Quantitative Modeling of MoS 2 –Solvent Interfaces: Predicting Contact Angles and Exfoliation Performance using Molecular Dynamics

International audienceThe large-scale synthesis of molybdenum disulfide (MoS2) using liquid-phase exfoliation, as well as several of its intended applications, including desalination membranes and biosensors, involve liquids coming into intimate contact with MoS2 surfaces. Molecular dynamics (MD) simulations offer a robust methodology to investigate nanomaterial/liquid interactions involving weak van der Waals forces. However, MD force fields for MoS2 currently available in the literature incorrectly describe not only the cohesive interactions between layers of MoS2 but also the adhesive interactions of MoS2 with liquids such as water. Here, we develop a set of force-field parameters that reproduce the properties of bulk 2H-MoS2, with special attention to the distinction between the covalent, intralayer terms and the noncovalent, interlayer Coulombic and van der Waals interactions. The resulting force field is compatible with MD force fields for liquids and can correctly describe interactions at MoS2–liquid interfaces, yielding excellent agreement with experimental contact angles for water (a polar solvent) and diiodomethane (a nonpolar solvent). In light of these results, previously published simulations studies on the desalination potential and biocompatibility of MoS2 devices need to be reevaluated. Potential of mean force (PMF) calculations demonstrate that use of our new force field can explain the current selection of solvents used in experimental studies of the liquid-phase exfoliation of MoS2 flakes, including the colloidal stability of the resulting dispersion. Our new force field enables an accurate description of MoS2 interfaces and will hopefully pave the way for simulation-aided design in applications including membranes, microfluidic devices, and sensors

Solvation structure of propane/propene in [C4mim][NTf2] ionic liquid

Data collected on the SANDALS instrument at the ISIS facility, RB1620078 Abstract: Supported ionic liquid membranes offer potentially lower-energy alternatives to cryogenic distillation for the separation and isolation of light gas olefins (ethene and propene) which are the only sources of starting materials to make polythene and polypropylene. This study will identify which features of the ionic liquid are responsible for differences in the solubilities of propane and propene in a key model ionic liquid. This will help gain understanding how the gases dissolve in the liquids, providing information that can direct the development of better liquid membranes for energy and cost-efficient recovery of these gases